It is known to utilize methodologies teaching relaxation which are directed at improving a patient's health. Many of these methods are based on correcting respiratory habits.
It has been suggested that the human cardio-vascular system can be regulated by using biofeedback methods. It has been further found that a human organism does indeed possess the possibility of feed back control or regulation of arterial blood pressure by changing the tone of blood vessels. It has been also found that the cardiovascular system generates by exhibiting high amplitude slow-wave oscillations which are superimposed upon the heartbeat. In practical terms such high amplitude low-frequency oscillations were associated with a tendency to decrease psycho-emotional strain, reduced tiredness and reduced chronic agitation (Vashillo E. G. et al, Research of Resonance Characteristics of a Cardio-vascular system, USSR Academy, 257 (1983)).
Based upon this discovery a therapeutic method was presented which comprised the steps of:
(a) registering a continuous heartbeat signal corresponding to a current heartbeat frequency of a patient; PA1 (b) converting the heartbeat signal to a an electrical signal to display the latter on a screen; PA1 (c) simultaneously with (b) displaying a reference signal corresponding to the low-frequency signal with high amplitude signal empirically determined prior to the experiment; and PA1 (d) modifying the patient behavior to gradually adjust the amplitude of the electric signal. PA1 first means for registering a subjects's current respiration rate and for converting the latter into a first electrical signal; PA1 second means for registering a current heartbeat of the subject and for converting the latter into a second electrical signal; PA1 monitor means operatively connected with the second means for displaying the second signal and a reference signal juxtaposed with the second signal and having a frequency arbitrarily selected from a predetermined frequency range; PA1 processing means for spectrally analyzing the first and second electrical signals and for generating a resulting signal corresponding to a phase shift therebetween; PA1 selecting means operatively connected with the processing and display means for selecting another frequency from the predetermined range of the displayed reference signal in response to the resulting signal, the other frequency being so selected as to gradually minimize the phase shift. PA1 a) continuously measuring heartbeat and respiratory rates of a subject and converting the rates into respective heart sinusoidal and respiratory electrical signals; PA1 b) selecting a sinusoidal reference signal with a first frequency lying in a frequency range of 0.01 to 0.14 Hz; PA1 c) simultaneously displaying the reference and heart signals to the patient PA1 d) instructing the patient to modify the respiratory rate according to the sinusoidal reference signal; PA1 e) spectrally analyzing the respiratory and heartbeat signals, thereby defining a phase shift therebetween; PA1 f) controllably selecting another frequency of the displayed reference signal within the predetermined range thereby minimizing the phase shift obtained in step (e); PA1 g) repeating steps (c) through (f) until the phase shift between the heart signal and the modified respiratory signal approaches "0" thereby determining an optimum breathing frequency corresponding to a resonance frequency wave characteristic unique for the patient's cardiovascular system; and PA1 i) training the patient to impose high-amplitude oscillations at the resonance frequency upon his heart rate. PA1 f.sub.1) decreasing the respiratory rate if the phase shift is less than zero, and PA1 f.sub.2) increasing the respiratory rate if the phase shift is more than zero. PA1 pulse rate decreases to an average 7-10 beats per minutes among children and to 5-6 beats per minute among athletes PA1 arterial pressure is normalized; PA1 the blood circulation in peripheral parts of the body improves; and PA1 the speed of voluntary muscle relaxation increases. PA1 imposing slow wave oscillation on blood pressure in all arterial blood vessels, even the smallest ones; PA1 stimulation of the brain by baroreceptor impulses; and PA1 training of the central and autonomic nervous systems. PA1 30 subjects of professionally trained athletes whose ages ranged from 19 to 22 years old were selected. Using further random selection half of the subjects has been assigned to the control group and the other half to the experimental group. The experimental group underwent 20 minutes of relaxation respiration procedure once a day for 10 consecutive days. All subjects were tested using a special polymyographical procedure on the first, fifth and tenth days. The procedure has been designed to reveal existing voluntary muscle relaxation disorders, to evaluate inhibition activity and to process balance in the central nervous system. PA1 (a) displaying a position of an image on a display to the subject while controlling the position by the heartbeat of the subject; PA1 (b) causing the subject, by control of a breathing pattern of the subject, to voluntarily shift the image in a targeted manner on the display, thereby superimposing upon the heartbeat the resonance frequency wave characteristic of the subject; and PA1 (d) conditioning the subject to produce the resonance wave by controlling the respiratory rate of the subject for improvement of a biological or emotional state of the subject. PA1 (a) measuring heartbeat of the patient; PA1 (b) subjecting the heartbeat of the patient measured in step (a) to a Fourier analysis to determine a resonance frequency superimposed on the heartbeat and specific to the patient in a frequency range of 0.01 to 0.14 Hz; PA1 (c) monitoring of the resonance frequency while instructing the patient to breathe at faster and slower rates until a breathing rate of the patient matches the resonance frequency and a phase difference between the breathing rate and the resonance frequency is at a minimum; and PA1 (d) conditioning the patient to breathe at that rate which matches the resonance frequency and the phase difference is at the minimum. PA1 (e) displaying a sine wave representing the resonance frequency on a display screen viewable by the patient; PA1 (f) displaying a wave representing an actual breathing rate of the patient on the same screen; and PA1 (g) demonstrating to the patient progressive approach of waves to a condition of minimum phase difference.
During the treatment a patient observed a signal corresponding to his present heartbeat rhythm and adjusted the latter to a plurality of sequentially shown sinusoidal signals with 13,12,11,10,9 and 7 second periods respectively. A frequency of that sinusoidal electric signal which provided a maximum amplitude of the signal corresponding to the patient's current heart rate oscillations has been defined as the "resonance" signal (Chernigovskaya N .B. et al, Voluntary Regulation of Cardio Vascular System for Correction of Functional Conditions of a Patient Suffering from Nerousis, USSR Academy of Science, 58 (1990)).
Thus method was both time consuming (taking approximately one hour) and imprecise because the determination of the "resonance" frequency was based on six discrete attempts corresponding to respective periods of the above mentioned sinusoidal signals. Although the "resonance" frequency only slightly depends on a given condition of a patient, an hour long procedure still can undesirably affect precision of determination of such frequency.
It has been also reasoned that "[T]he immediate cardiovascular effects of respiration summate with the baroreceptor reflexes to produce a "resonance frequency"... expected to increase the amplitude of heart oscillations." P. Lehrer, E. Vashillo., et al., Respiratory Sinus Arrhythmia Versus Neck/Trapezius EMG an Incentive Inspirometry Biofeedbak for Asthma: A pilot Study, Applied Psychophysiology and Biofeedback, vol. 22, 97 (1997). The results were consistent with Vashillo's theory that RSA (respiratory sinus arrhythmia) biofeedback "exercises homeostatic autonomic reflex mechanism through increasing the amplitude of cardiac oscillation." Id., at 95.
However a concrete relationship between the respiratory and heartbeat frequencies has been developed heretofore in this context.
The U.S. Pat. No. 4,580,575 describes a method of correcting the failure of heartbeat by employing heartbeat and respiration detection circuits. However the latter is done for controlling upper and lower heartbeat limits beyond which a patient's life may be in jeopardy.